The World of Neptune
by Soulsilverlord
Summary: When almost all the Riders fall to Dark Decade, DiEnd follows in pursuit while Tsukasa abandons the Decadriver to preserve it after his defeat. When the Driver falls into the hands of Noire, the entire gang is pulled into an all out war between the remaining Riders and Dark Decade's army. Post-Victory
1. Prologue

The World of Neptune

By: Soulsilverlord

…

Kamen Rider © Toei

Hyperdimension Neptunia © Compile Heart

…

**Prologue: The Dark One**

_ "ACCEL: MAXIMUM DRIVE!" a robotic voice called aloud as a man clad in red armor performed a powerful kick; striking down the monster he was fighting. He quickly turned, only to be hit by another strike from an oncoming enemy. The enemy sneered at him before striking at the man once again. However, this time the strike caused the man to suddenly turn to stone._

_ Alongside the red armored man several others fought similar creatures, called the Psyches. Their origin unknown, all they know how to do is turn living creatures to stone. A man that was in red, yellow, and green armor noticed the man in red fall to the ferocious creature._

_ "ACCEL!" he yelled out, striking his own Psyche down. Grabbing two new medals from his holster he replaced the ones already in his buckle. He quickly grabbed onto a scanner, located on his belt, and scanned the three medals located in the center of his belt buckle. _

"_**TAKA! KUJAKU! CONDOR! TAJADOR!" **_

___The scanner called the three full medals at they converged onto his. The newly formed red armor shined brightly. He leapt up into the air and scanned the three medals within them once again._

"_Scanning CHARGE!"_

_ He quickly flew through three red rings that emerged from his belt and kicked through them. This caused the immediate deaths of several Psyches; unfortunately the red bird hero was also struck by the touch causing him to become stone. This pattern continued and claimed the lives of several other heroes. A man with diamond armor, one with a lion motif, and several others were also turned to stone._

_ Only two stood against the invaders. One was cyan in color and wielded a gun similar to his armor. The other was magenta and wielded a sword that was in the shape of a photo album. They continued to fight against the menace, causing them to fall back._

_ "These things are certainly a pain in my ass." The one in magenta spoke as the monsters fell back from the front line._

_ "We might get to see who's behind this now that the lot has been cleared out." The cyan one smirked under his helmet._

_ "I think your wish just came true… Look ahead." The magenta one called aloud as the Psyches stopped and aligned themselves into two straight lines. Someone began to walk down the middle between the two lines. The person stopped and began to speak._

_ "How does it feel, Riders? My army has done well, has it not?" the person spoke aloud. It was a female who spoke. "Now only two inadequate Riders remain."_

_ "Why would you do something like this? Destroying the world's protectors, why?" the magenta one spoke._

_ "Why might I do this? I do this because the Riders are no longer needed. There should only be one heroine in this story and it will be me. Now Decade and DiEnd, meet your match!" she yelled out, putting a black belt around her waist. It was similar to the white one that Decade wore around his own waist. She pulled out a card and inserted it into the belt. _

_** "HENSHIN!" **__the girl yelled out as she closed the belt. _

_**KAMEN RIDER: DECADE**_

_ The belt announced in a dark and sinister voice. Nine transparent armors appeared around her, and each one converged into her before forming a black, blue, and gold copy of Decade._

_ "Looks like we got ourselves a live one, eh Tsukasa? Shouldn't be too hard of a fight." DiEnd smirked under his helmet and pulled out a large device._

_ "I see going straight for the finisher. Looks like we got no choice." He pulled out his own matching device._

_ "Are you two done? I'm going to finish you both right now!" she said crazily. "Now watch as you both become stone and locked in this dimension." She removed a card from her Ride Booker and inserted it into her belt._

_**FINAL ATTACK RIDE: D-D-DECADE**_

___The two opposite Riders quickly placed their own devices onto their belts, upgrading to their Complete Forms. The Dark Decade leapt up into the air and suddenly it was as if every other fallen hero was with her. DiEnd placed a card into his gun and loaded it._

_**ATTACK RIDE: INVISIBLE**_

___"Kaitou!" Decade yelled out as DiEnd apparently avoided the attack. Decade could only stand as he pushed an LED on his belt, hoping to avoid the attack._

_**Wizard. KAMEN RIDE. Infinity!**_

_ A diamond rider appeared next to him as Decade's body braced for the attack of the many riders. Each one striking down on him, causing him to fall the ground for a final time. The Dark Decade smirked as her transformation broke, alongside Decade's own. She went on one knee and removed the Ride Booker from his belt, alongside the K-Touch he used to assume Complete Form._

_ "You won't be needing these anymore." She said, removing the cards from the booker and throwing the booker back down to Tsukasa. "Any last words before I turn you to stone as well?"_

_ "Nope. Only an action could end this." Tsukasa said cryptically. He leapt up quickly and kicked his enemy, causing her to fall. "This will use the rest of my energy but…" He did not complete his sentence as he opened a portal to a random parallel universe. Taking his transformation belt, the Decadriver, he threw it into the portal that opened. "Kaitou! If you're still here, it's all up to you now!" A Psyche quickly slashed at Tsukasa, causing him to turn to stone._

_ "Not like he can do anything now that I have these." The Dark Decade spoke to herself. "Now I can take over all the different worlds. No one can stop me. First, I need to dispose of those damn fruit riders before they become a nuisance." She waved her hand and disappeared through a portal to a parallel world._

_ DiEnd reappeared and quickly went to Tsukasa's side. "Sorry I had to do that. Hopefully, you understand neither of us would have been able to beat that. I'll find her and stop her from destroying the World of Gaim." He got up and summoned his own portal and chased after Dark Decade to the World of Gaim._

…

_ Somewhere else a portal opened in the sky, spitting out a small white belt and a book with a single card. Landing in the grass the two items landed next to each other in plains like area. _

_ "I wonder what this thing is." A voice chimed out, as a hand reached down and picked up the two items. The voice belonged to a young woman with black pigtails. _

**A/N: Yes I am back after a short hiatus away. Now I have a new story for you all that I hope you enjoy. It's a crossover between Hyperdimension Neptunia and the Kamen Rider series. While most of the story is post-Victory and takes place in both the Hyperdimension and Ultradimension, I hope to add some stuff with Gaim in it eventually. As for now, enjoy! Please review and tell me what you would like to see in future chapters.**


	2. Chapter 1

The World of Neptune

By: Soulsilverlord

…

Kamen Rider © Toei

Hyperdimension Neptunia © Compile Heart

…

**Chapter 1: CPU Black Heart and the Fang **

"The lady wishes for you to retrieve this." A scratchy voice said, as a large white hand handed a piece of paper to the man opposite of him. "Apparently, it could cause her plan to fail even with the Riders out of the way."

The man opposite of the creature was dressed in black attire. A light grey cape hung around his neck and touched the floor. "The Decadriver… I see, this seems to be a problem in our way isn't it. Don't worry I have it all under control. Our lady's wish will be granted."

"That tone doesn't fit when speaking of her highness. I'd be a bit more careful." The creature replied, reeling back into the darkness to continue on his orders. "Be careful, the world the idiot threw it into is uncharted territory."

"I'm more than careful. Don't worry your creepy little hands, I'll get the job done." The black robed man said back, he quickly got up from his own seat and left the room. "I know the right way to deal with this, and in a fun enough way."

…

Noire bent down and picked up the strange looking device that was in the grass. It was a large white piece of metal with strange markings all over it. When held horizontally it said the word "DECADE" on it. Along the middle were mysterious markings, surrounding the magenta glass in the center of it. She looked at the rest of it and saw nothing wrong with it.

"Is it some sort of machine? It looks so clean and industrialized." She said to herself, as she placed it back down on the ground and picked up the book-like thing. "This books is made of… metal?" She opened up the book to reveal two folder-like entities on both sides of the book. One seemed to only have one card, which showed nothing on it, and the other side had three blacked out cards as well. The two items had matching color schemes, causing Noire to assume that the two were one in the same.

"I should take this back to Lastation and have it looked at. I've never seen anything constructed like this." She removed the cards from the book as she began to walk back to Lastation's Basillicom. Each one was more of a dark silhouette with something clearly behind them, yet obscured too much. Eventually, she arrived back in Lastation.

Screaming was heard from all direction as citizens panicked and fled from the city, while Noire quickly found someone on the ground lying motionlessly. It was a dying soldier.

"Hey are you alright?" she asked, pulling him onto his back. A sharp white stone was in his abdomen.

"I am fine Lady Black Heart, but he's on the loose causing a panic. It's a snow-white creature pulling these things out his body. You must save them…" the soldier went unconscious. He was seemingly fine as another soldier hoisted him away. Noire turned and ran back toward her Basillicom.

"What's going on here exactly? Nothing could cause this big of a panic that quick…" she thought to herself as she returned to her home. Upon opening her door, she saw something that horrified her more than anything she had endured in the past, including the whole ASIC and alternate dimension thing. Her younger sister, Uni, was lying down on the ground and badly beaten. A maniac laughter was heard from the ceiling.

"Do you like what I've done with her? I certainly thought she would have put up more of a fight than that." The voice sounded, it was filled with insanity.

Noire quickly ran to her younger sister. She was unconscious, but no serious injuries on the outside. "Uni… Who are you, you sick bastard!"

"Yes, who indeed am I? I'm like a puppet, a being with no soul, just being told what to do. I received information that you found our precious little item." The man leapt down from the rafters, onto the ground in front of Noire. He was wearing white goggles along with white clothes. Around his neck was a white scarf, and on his face was the smile of a madman. "Now I will be taking my item back now."

"You mean this? Why would you even want it?" she yelled aloud, revealing the Decadriver and Ride Booker.

"Yes, now hand it over like a good little girl."

"No, you went as far to hurt Uni and all those other people. IN MY NATION?!" she yelled out angrily. A flash quickly blinded the eyes of the clearly insane man. He opened his eyes to see a more mature transformed Noire. She was a bit taller, dressed in a black latex suit, her hair was white, had some random extra things floating around her.

"So you want to fight? I'll be glad to do so." He said in return, pulling out a red belt buckle from his pocket. He quickly stuck it in front of his waist and it immediately strapped itself around his waist.

"What do you plan to do with that?"

"I'll tell you what I plan to do." He snapped his fingers and a small roar were heard. A small dinosaur like creature appeared and leapt into his hand. He quickly pulled the tail and turned it around a bit. He clicked a small button on the tail, which greatly resembled a flash drive.

_**FANG**_

__**"HENSHIN!" **he placed the drive into his device on his belt and quickly folded it in. It now greatly resembled a dinosaur. **"FANG"**'

"Let's get this show on the road, eh?" he quickly hit the tail on his belt once.

_**SHOULDER FANG**_

__A large white fang erupted from his shoulder, which he pulled out. He ran forward and recklessly slashes at Black Heart with it. Dodging out of the way, she summoned her own weapon and hit the fang, destroying it instantly.

"A little bit better than the younger sister. Of course I did attack her from behind." He laughed a bit more, summoning another shoulder fang.

"You truly are a coward, aren't you?" Black Heart questioned, attacking at an incredible speed.

"Maybe so, but then again. I don't really care as long as the job gets done."

"That's quite bold you to say, especially when you're about to lose."

"I don't lose, trust me. If not I would have already had to resort to a really cheap tactic." He pushed the tail twice this time.

_**ARM FANG**_

__Another fang erupted from his body, this time on his arm. He leapt up and quickly slashed at Black Heart, tearing her body suit and skin. She fell to the ground, finding it hard to recover from the attack. Fang attacked again and slashed at her several more times with his arm. He stopped and busted out laughing like a madman.

"You sure do know how to keep your guests entertained, but now I'll kill you and take back my item." He pushed the tail in three times this time.

**FANG MAXIMUM DRIVE**

He jumped up into the air and began to spin along with a fang erupting from his legs, feet, arms, and hands. "Fang Tornado!"

"Not like this. I've fought tougher than you! INFINITE SLASH!"

_TO be continued…._


	3. Chapter 2

The World of Neptune

By: Soulsilverlord

…

Kamen Rider/Super Sentai © Toei

Hyperdimension Neptunia © Compile Heart

…

**Chapter 2: The Red Hero **

Everything went black for Noire. The two powerful finishing attacks collided, causing a rather large explosion. She fluttered her eyes, only to see a large void of nothingness. It was like the night sky with several planets surrounding her. She got up and realized she was no longer transformed.

"I see you're finally awake." A voice called out. "I was wondering when you would finally get up."

Noire looked around to see a rather old looking man before her. The man was wearing a black turtleneck and a black leather jacket. He smiled before walking up to her.

"So you're the one going to save the multiverse." He said to her, turning around and waving his hand causing the planets to stop moving.

"Who are you? What is this place?" Noire asked the man.

"My name is Tsuyoshi Kaijo, also known as Akaranger." The older man said, pulling a small key out from his pocket. On closer inspection, the key resembled some sort of superhero. It was clad in red with a small blue visor on top of its head. "This place is the entrance to the many worlds. They are being destroyed as we speak."

"Wait, what's going on?" Noire demanded from the man, stomping her foot on the ground that wasn't really there. "What was that thing that attacked my city?"

"I see, you're all business. Very well then I will tell you everything I know." The man said, placing the key back into his pocket. "Like I said the multiverse is being destroyed. One of the soldiers of the army destroying it was whom you fought. He was a puppet using power to become Kamen Rider Fang."

"What is a Kamen Rider? Why did it attack Lastation of all places?"

"A Kamen Rider is someone who transforms to protect all of humanity, unfortunately there are no more Kamen Riders left. My comrade, Kamen Rider #1, also fell during the war. The last one to stand was a young man by the name of Tsukasa. He led the final attack on the army in the World of W. The Kamen Riders lost and as punishment they were turned into stone."

"Well what are you if you're not a Kamen Rider. You have that little key in your pocket." Noire asked the older man, now interested in what he way fully saying. "And you said that Kamen Rider transform to protect humans; then why did that Fang attack my world?"

"I'm a member of the Super Sentai. Another group of heroes who protect Earth from the evil that threatens it. Also, like I said the man you fought against was a puppet that you probably destroyed. He is a carbon copy of a real Rider." Kaijo said, waving his hand again causing a small screen to appear. Inside the screen, Noire was asleep in her bed. "Right now you are asleep in your world, however as we speak time marches on in your world. More will attack your world in hopes of conquering."

"You said I was the one going to save the multiverse, right? What can I do? I could barely stand to that Fang guy… I'm a goddess and a puppet almost beat me…" she said, her state falling a bit into despair and falling to her knees. "I won't be able to save anyone." Her mind went back to when Rei Ryghts almost destroyed the two different worlds. As she sat on her knees she felt someone touching her soldier.

"You have comrades as does everyone. You won't fail as long as you're not alone. I have to protect the final world from falling alongside the remaining Sentai and Riders. We won't fail as long as we work together, just like you and your friends have in the past. You have the power to save everyone. Remember the things you found? Those belonged to a Kamen Rider, more importantly they belonged to Decade. Use those cards to save these worlds." He waved his hand again, causing the worlds to begin moving again. Another figure appeared out of the shadows of nowhere.

"Sempai, we don't have enough power to allow this connection." The man said. He was much younger, somewhere in his early twenties, and wore a red plaid shirt and jeans. "We must return to the World of Gaim now."

"I see. Thank you Takeru-san, begin to end our connection between the worlds." The young man shook his head and disappeared.

"Who was that?" Noire asked, getting up to her feet once again. She felt revitalized after Kaijo's speech.

"That was one of the last remaining Sentai members, Takeru Shiba, also known as Shinken Red. He and the other members of the Samurai Sentai Shinkenger are using their mojikara to keep a connection between these worlds. This connection will end soon. Find your comrades and end the dark reign of the army who opposes the happiness of all humanity." Kaijo said once again. "Defend the worlds from Dark Decade and her army of Psyches!" he turned around and a faint glow appeared around him. Noire simply watched as he transformed into Akaranger and disappeared into the darkness. Suddenly, the darkness around her exploded into white light. She saw all the Sentai. They were all suited and ready to protect their worlds. One-by-one they all disappeared into the light, except for one. A red hero walked up to her.

"It all starts here, a new journey that involves everyone from every place in the universe. My last journey saved a planet that I could have cared less about. Let me pass some advice to you. Make sure you have a team that can do everything properly. I know I did and it turned out that was the best possible thing I could do. Finally, make sure to make it your showiest performance of all time. Do that and everything will turn out to be the best in the end." He disappeared like the rest, leaving Noire alone once again.

"You're story begins here."

To be continued…


End file.
